1. Field of the Invention
The invention relates generally to soft tissue fixation devices. More particularly, the invention relates to threaded fixation devices for securing soft tissue to bone. Still more particularly, the invention relates to sutureless soft tissue fixation devices.
2. Description of the Prior Art
In the course of certain surgical procedures, soft tissue is attached to a selected bone surface either directly, via suture or some type of implant device (i.e. an anchor), or indirectly via an implant device to which suture is attached so it may then be tied to the soft tissue to hold it in place. Such implant devices may be bioabsorbable and generally have a bone-attachment or anchor portion, for securing the device to a selected bone or other firm tissue, and a soft-tissue-attachment portion for securing the soft tissue to the device. It will be understood that the terms "soft" and "bone" are relative and the devices disclosed herein may be used to attach a relatively soft material to a relatively hard material. The term "bone" as used herein thus includes any firm tissue which can anchor the device. The term "base" may be used occasionally herein to refer to such anchoring material. The anchor portion of these soft tissue attachment devices is generally elongated and may be, for example, in the form of a generally cylindrical body having a screw thread, deformable radially extending annular ribs or radially extending, circumferentially spaced, relatively resilient barbs. Some devices have a hollow expandable sleeve, which is inserted into place within a pre-formed hole in a bone, and a solid core which is inserted into the associated sleeve to expand it against the bone wall of the pre-formed hole.
The soft tissue attachment portion of these devices is in the form of a means to hold soft tissue fixed relative to the anchor portion. This holding function is done generally by a suture extending between the anchor portion and the soft tissue, or by another structure. If suture is used, the device is sometimes referred to as a suture anchor with the suture generally being either threaded through an eyelet or other aperture formed into the anchor, or knotted within an aperture on the anchor or otherwise secured to the anchor, prior to the anchor being implanted. If suture is not used, the devices are sutureless in that they employ a transverse structure or head attached to the anchor portion so that the soft tissue is maintained adjacent to the bone surface by a relatively large head attached to one end of a relatively narrow anchor portion.
Anchors may be used to attach soft tissue such as ligaments, tendons, muscles, etc. to a surface from which the soft tissue has become detached. For example, the rotator cuff may be reattached to the humeral head during a shoulder repair. Anchors may also be used to secure soft tissue to supplementary attachment sites for reinforcement. For example, in urological applications anchors may be used in bladder neck suspension procedures to attach a portion of the bladder to an adjacent bone surface. Such soft tissue attachments may be done during either open or closed surgical procedures, the latter being generally referred to as arthroscopic or endoscopic surgery. The terms "arthroscopic" and "endoscopic" may be used interchangeably herein and are intended to encompass arthroscopic, endoscopic, laparoscopic, hysteroscopic or any other similar surgical procedures performed with elongated instruments inserted through small openings in the body.
The prior art includes numerous types of suture anchors adapted to be secured in the bone, sometimes directly in one step and sometimes in pre-drilled or pre-formed holes or tunnels. These anchors are generally "push-in" or "turn-in" type anchors and once placed in bone require that soft tissue be sutured to the anchors. Prior art push-in suture anchors are generally elongated, cylindrical devices having annular ribs or radially extending barbs and are required to be pushed or hammered directly into bone or into a pre-formed bone tunnel (exemplified by U.S. Pat. Nos. 5,102,421 (Anspach, Jr.); 5,141,520 (Goble et al.); 5,100,417 (Cerier et al.); 5,224,946 (Hayhurst et al.) and 5,261,914 (Warren)). Pushing an anchor into place may in some circumstances be undesirable because of potential trauma and damage to surrounding bone tissue, and has limited applicability in certain situations such as, for example, where the location of the bone tunnel or pre-drilled hole is not axially aligned with an arthroscopic portal to permit transmission of the impacting force through an impactor to the anchor. Furthermore, a pushed-in suture anchor is not easily removable without damaging the bone into which it has been placed. Consequently, turn-in or threaded suture anchors are often used as exemplified by U.S. Pat. Nos. 5,156,616 (Meadows et al.) and 4,632,100 (Somers et al.). Such anchors are generally elongated, cylindrical devices having a plurality of threads and a pointed tip. Depending upon the type of threaded anchor, the insertion procedure may enable direct threading of the anchor into the bone or it may sometimes require that a pilot hole first be drilled or formed into the bone, the hole then either enables an anchor to be screwed in or enables threads to be tapped to receive the anchor.
Push-in sutureless soft tissue anchors are known and have a transverse head which enables a user to avoid the suturing step, but these devices are not easily removable. Turn-in sutureless soft tissue anchors are also known and these devices have either a multi-part construction, with the head separate from and not integrally formed with the anchoring body, or are otherwise limited in strength or ease of manufacture and require a relatively complex insertion procedure. Overcoming the disadvantages of prior art devices while making these a device from bioabsorbable materials requires a design which is strong enough to withstand insertion stresses and use prior to absorption by the body.
In procedures utilizing indirect suturing of soft tissue to bone, the suture may either be first anchored by suture anchors to the bone before passing the suture through the soft tissue, or the tissue may first be sutured and the anchor may then be slid down one leg of the suture and then implanted into bone. In procedures utilizing sutureless devices which directly attach soft tissue, the devices are inserted through the soft tissue.
It would be desirable to simplify not only the method used to attach soft tissue to bone in certain surgical procedures but also the manufacture of sutureless soft tissue fixation devices.
It is accordingly an object of this invention to produce a system for inserting threaded soft tissue anchors into bone.
It is also an object of this invention to produce a unitary, threaded sutureless soft tissue anchor.
It is a further object of this invention to produce a bioabsorbable threaded sutureless soft tissue anchor.
It is yet another object of this invention to produce a threaded, sutureless soft tissue anchor which can be embedded into bone while minimizing trauma to the surgical site.
It is another object of this invention to produce a system for the sutureless fixation of soft tissue to bone.
It is yet another object of this invention to produce a sutureless soft tissue fixation system capable of securing soft tissue to a selected site without the need for a guide wire or similar intermediate step.
It is also an object of this invention to produce a sutureless soft tissue fixation system capable of driving into bone a soft tissue anchor made of a relatively soft, preferably bioabsorbable material.